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iron sulphide (CuFeS2), an important ore of copper. The name copper-pyrites is from the Ger. Kupferkies, which was used as fpr back as 1546 by G. See also:

Agricola; chalcopyrite (from xaArcos, " copper," and pyrites) was proposed by J. F. Henckel in his Pyritologia, See also:

ODER (Lat. Viadua; Slavonic, Vjodr)

oder Kiess-Historie (1725). By the ancients copper-pyrites was included with other minerals under the See also:

TERM

term pyrites, though the copper-ore from See also:

Cyprus referred to by See also:

Aristotle as chalcites may possibly have been identical with this See also:

MINERAL

mineral. Chalcopyrite crystallizes in the tetragonal See also:

SYSTEM

system with inclined hemihedrism, but the See also:

FORM (Lat. forma)

form is so nearly cubic that it was not recognized as tetragonal until accurate measurements were made in 1822.

Crystals are usually See also:

TETRAHEDRAL

tetrahedral in aspect, owing to the large development of the sphenoid P {111}. The faces of this form are dull and striated, whilst the smaller faces of the complementary sphenoid P' {III} (fig. 1) are See also:

bright and smooth. The See also:

COMBINATION (Lat. combinare, to combine)

combination of these two forms produces a figure resembling an See also:

OCTAHEDRON (Gr. 6K-rw, eight, Mpa, base)

octahedron, the See also:

ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle between P and P' being 70° 7k', corresponding to the angle 700 32' of the See also:

REGULAR

regular octahedron. The other faces shown in fig. r are the basal pinacoid, a See also:

FOOL (O. Fr. fol, modern fou, foolish, from a Late Latin use of follis, bellows, a ball filled with air, for a stupid person, a jester, a wind-bag)

fool}, and two square pyramids, b { IoI } and c 1201). Crystals are usually twinned, and are often complex and difficult to decipher. There are three twin-See also:

LAWS

laws, the twin-planes being (III), (tor) and Oro) respectively. Twinning according to the first See also:

law is effected by rotation about an See also:

AXIS (Lat. for " axle ")

axis normal to the sphenoidal See also:

FACE (from Lat. fades, derived either from facere, to make, or from a root fa-, meaning " appear "; cf. Gr. cbatvstv)

face (III), the resulting form resembling the twins of See also:

BLENDE, or SPHALERITE

blende and See also:

SPINEL

spinel. Twinning according to the second law can only be explained by reflection across the See also:

PLANE

plane (ror), not by rotation about an axis; chalcopyrite affords an excellent example of this comparatively rare type of symmetric twinning. Interpenetration twins (fig. 2) with (1 ro) as twin-plane are of very rare occurrence. Crystals have imperfect cleavages parallel to the eight faces of the See also:

PYRAMID

pyramid c 12011.

The fracture is conchoidal, and the material is brittle. Hardness 4; specific gravity 4.2. The See also:

COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour is See also:

brass-yellow, and the lustre metallic; the streak, or colour of the See also:

POWDER (through O. Fr. puldre, modern poudre, from Lat. pulvis, pulveris, dust)

powder, is greenish-See also:

black. The mineral is especially liable to See also:

SURFACE

surface alteration, tarnishing with beautiful iridescent See also:

COLOURS, MILITARY

colours; a See also:

BLUE (common in different forms to most European languages)

blue colour usually predominates, owing probably to the alteration of the chalcopyrite to covellite (CuS). The massive and compact mineral frequently exhibits this iridescent tarnish, and is consequently known to miners as " See also:

peacock ore " or " peacock copper." The massive mineral sometimes occurs in mammillary and botryoidal forms with a smooth brassy surface, and is then known to Cornish miners as " blistercopper-ore." Chalcopyrite or copper-pyrites may be readily distinguished from iron-pyrites (or pyrites), which it somewhat resemblesin See also:

APPEARANCE (from Lat. apparere, to appear)

appearance, by its deeper colour and See also:

LOWER

lower degree of hardness: the former is easily scratched by a See also:

KNIFE (0. E. cuff, a word appearing in different forms in many Teutonic languages, cf. Du. knijf, Ger. Kneif, a shoe-maker's knife, Swed. knif; the ultimate origin is unknown; Skeat finds the origin in the root of " nip," formerly " knip "; Fr. canif is a

knife, whilst the latter can only be scratched with difficulty or not at all. Chalcopyrite is decomposed by nitric See also:

ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid with separation of See also:

SULPHUR

sulphur and formation of a See also:

green See also:

SOLUTION (from Lat. solvere, to loosen, dissolve)

solution; See also:

AMMONIA (NH3)

ammonia added in excess to this solution changes the green colour to deep blue and precipitates red ferric hydroxide. The chemical See also:

formula CuFeS2 corresponds with the percentage See also:

composition Cu =34'5, Fe =30'5, S = 35.0. Analyses usually, however, show the presence of more iron, owing to the intimate admixture of iron-pyrites. Traces of See also:

gold, See also:

SILVER

silver, See also:

SELENIUM [symbol Se, atomic weight 79.2 (O=16)]

selenium or See also:

THALLIUM

thallium are sometimes See also:

PRESENT

present, and the mineral is sometimes worked as an ore of gold or silver. Chalcopyrite is of wide See also:

DISTRIBUTION (Lat. distribuere, to deal out)

distribution and is the commonest of the ores of copper. It occurs in metalliferous See also:

VEINS

veins, often in association with iron-pyrites, See also:

CHALYBITE

chalybite, blende, &c., and in See also:

CORNWALL

Cornwall and See also:

DEVON, EARLS OF

Devon, where it is abundant, with cassiterite. The large deposits at See also:

FALUN

Falun in See also:

Sweden occur with See also:

SERPENTINE

serpentine in See also:

GNEISS

gneiss, and those at See also:

MONTECATINI

Montecatini, near See also:

VOLTERRA (anc. Volaterrae)

Volterra in the See also:

province of See also:

Pisa, serpentine and See also:

GABBRO

gabbro.

At See also:

RAMMELSBERG, KARL FRIEDRICH AUGUST (1813-1899)

Rammelsberg in the Harz it forms a See also:

bed in argillaceous schist, and at See also:

Mansfield in Thuringia it occurs in the Kupferschiefer with ores of See also:

nickel and See also:

COBALT (symbol Co, atomic weight 59)

cobalt. Extensive deposits are See also:

MINED

mined in the See also:

UNITED

United States, particularly at See also:

Butte in See also:

MONTANA

Montana, and in See also:

NAMAQUALAND

Namaqualand, South See also:

Africa. Well-crystallized specimens are met with at many localities; for example, formerly at Wheal Towan (hence the name towanite, which has been applied to the See also:

SPECIES

species) in the St See also:

AGNES, SAINT

Agnes district of Cornwall, at See also:

FREIBERG, or FREYBERG

Freiberg in See also:

Saxony, and See also:

JOPLIN

Joplin, See also:

MISSOURI

Missouri. (L. J.

End of Article: COPPERMINE

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